Numerous varieties of crossbows are known, wherein a plane of arrangement and bending of limbs, on one hand, as well as a plane of arrangement of cams and passage of cables and a bowstring, on the other hand, are parallel to each other (or even coincide). When such a crossbow is used for making a shot said planes are located horizontally. This crossbow design is most common, and a typical example is disclosed e.g. in U.S. Pat. No. 9,297,604.
Parallelism or coincidence of the plane of arrangement and bend of limbs and the plane of arrangement of cams and passage of cams and a bowstring results in that transverse dimensions of a crossbow, which are defined mainly by a spread of limbs, are great. A reduction of the spread of limbs causes the necessity of using limbs having low elasticity in order to maintain a high initial speed of an arrow. This causes known difficulties in using the crossbow as well as higher load on components of the crossbow, since a higher force is required for drawing a bowstring.
Also known are crossbows which limbs are located vertically when making a shot. These crossbows have a very small width. This is obtained by arranging limbs, cams, a bowstring and cables in a vertical plane. Examples may be found in U.S. Pat. Nos. 8,622,050 and 8,671,923, which describe the crossbows having the limbs with the cams installed thereon that are arranged in a vertical plane in such a way that the first limb is located below the frame and the second limb is located above the frame. The bowstring and cables connect said cams in the vertical plane too. Said cables cross the crossbow frame, thus creating a friction node lowering an initial speed of an arrow when shooting. The bowstring, when being drawn, is moved along the crossbow frame in the vertical plane. Apparently, this arrangement of the limbs reduces dimensions of the crossbow in width, but significantly increases dimensions in height. Furthermore, a movement of the bowstring in the vertical plane causes inconvenience in placing the arrow and holding such the crossbow.
In fact, the above-described known vertical crossbows do not differ in any way from the crossbows having commonly arranged limbs (i.e. horizontally), and therefore show the same drawbacks as the crossbows with commonly arranged limbs.